1. Field of the Invention
This invention relates to a motor operation controller and an insulation type bidirectional DC voltage converter for accommodating different power supply voltages.
2. Description of Prior Art
Power supply voltages to a motor operation controller vary substantially depending on the application of a motor and the country or region where the motor is used. For example, in Japan, generally the home power supply voltage is 100 VAC, while the industrial power supply voltage is 200 VAC. In overseas countries, the industrial power supply voltages are 200-230 VAC, 380 VAC, 400 VAC, and 415 VAC (Europe) and 240 VAC and 460-480 VAC (USA). Generally, the industrial power supply voltages are roughly classified into 200 VAC, 240 VAC, 380 VAC, 415 VAC, and 480 VAC.
The motor is used in any operation state of acceleration, normal output, and deceleration. Thus, the motor operation controller requires two functions of feeding energy to the motor from an input power supply, which will be hereinafter referred to as a xe2x80x9cpower mode,xe2x80x9d and of returning rotation energy of the motor and a rotor secured to the motor to the input power supply by operating the motor as a generator, which will be hereinafter referred to as a xe2x80x9cregeneration mode.xe2x80x9d
FIG. 28 is a block diagram showing the main circuit part of a conventional motor operation controller, wherein numeral 1 is an input power supply, numeral 2 is a motor operation controller, and numeral 3 is a motor. The motor operation controller 2 is roughly divided into a converter section 4 for converting an AC input section and a DC. section bidirectionally and an inverter section 5 for converting DC into AC. In the converter section 4, numeral 6 is a rectifier made up of a diode bridge, etc., numeral 7 is a power supply inverter made up of a transistor bridge, etc., for outputting a power supply frequency, numeral 8 is a power supply inverter controller for controlling the operation of the power supply inverter 7, and numeral 9 is a smoothing circuit made up of an electrolytic capacitor, etc. In the inverter section 5, numeral 10 is an inverter for outputting a voltage, current, and frequency in response to the operation state of the motor 3, numeral 11 is an inverter controller for controlling the operation of the inverter 10, and numeral 12 is an interface circuit for receiving operation commands of the motor 3, such as acceleration, deceleration, and rotation speed, given from the outside.
FIG. 29 is a conventional example for accommodating power supply voltages incompatible with the voltage specifications of the motor operation controller 2 and the motor 3, wherein numeral 1a is an input power supply incompatible with the voltage specifications and numeral 13 is a transformer for converting a power supply voltage incompatible with the voltage specifications into a voltage conforming to the specifications.
FIG. 30 is a connection example involving a plurality of motor operation controllers 2a, 2b, and 2c and a plurality of motors 3a, 3b, and 3c. In the example, batch voltage conversion is made through the transformer 13 for supply to the motor operation controllers 2a, 2b, and 2c. The motor operation controllers 2a, 2b, and 2c receive motor operation commands a, b, and c, respectively, from the outside.
FIG. 31 is a circuit diagram shown in Japanese Patent Laid-Open 4-38192, wherein a DC voltage converter 20 is provided between a rectifier 6 in a converter section and an inverter section 5 for accommodating power supply voltages incompatible with the voltage specifications of the motor 3. In FIG. 31, numeral 21 is a primary smoothing circuit, numeral 22 is a secondary smoothing circuit, numeral 23 is a discharge resistor, numeral 24 is a discharge switch, and numeral 25 is a controller for controlling the DC voltage converter 20 and the inverter section 5.
Next, the operation will be discussed. First, the operation of the motor operation controller 2 in FIG. 28 will be described. In the power mode, the motor operation controller 2 converts an input AC voltage 1 into a DC voltage through the rectifier 6 and smooths the DC voltage by the smoothing circuit 9. Then, it again converts the smoothed DC voltage into an AC power supply of a voltage, current, and frequency required for operating the motor 3 by the inverter 10. When receiving an output of the inverter section 5, the motor is operated at a predetermined rotation speed. Next, in the regeneration mode, the inverter 10 operates so as to run the motor 3 as a generator. As a result, rotation energy of the motor 3 is fed back through the smoothing circuit 9 via the power supply inverter 7 to the input power supply 1, applying an electric brake. The inverter controller 11 controls the inverter 10 so as to drive the motor 3 in response to an external motor operation command received on the interface circuit 12. The power supply inverter 7 inputs the supply voltage magnitude, frequency, and phase, and voltage of the smoothing circuit 9. When the smoothing circuit voltage becomes greater than the power supply voltage as in the regeneration mode, the power supply inverter 7 is driven at the same frequency and phase as the input power supply, thereby feeding back the energy to the input power supply 1. Thus, the converter section 4 has a number of components, but a simple function, while the inverter section 5 has functions such as controlling the motor speed and rotation position and interfacing with an external controller and serves as the central function and fundamental operation of the motor operation controller 2.
Next, the conventional examples for accommodating supply voltages incompatible with the voltage specifications of the motor 3 will be discussed. The following three methods can be used for accommodating supply voltages incompatible with the voltage specifications:
Method 1: The withstand voltage, allowable voltage, and current of the motor operation controller 2 and the motor 3 are considered for selecting components and designing the structure in response to input voltages.
Method 2: As shown in FIG. 29, the transformer 13 is inserted between the input power supply 1a and the motor operation controller 2 for making voltage conversion.
Method 3: As shown in FIG. 31, the internal DC voltage converter 20 is provided.
According to Method 1, 200VAC motor operation controllers and 200-VAC motors cannot be used at 400 VAC when considering the withstand voltage, and cannot be used at 100 VAC when considering the current capacity of main circuit parts because a double current is required, although the voltage becomes a half as compared with 200 VAC. As a result, the motor operation controllers 2 and the motors 3 of different types must be provided for various power supply voltages.
According to Method 2, different types of transformers must be provided for various voltages.
According to Method 3, the motor 3 having specifications different from the power supply voltage la can be used, but a transformer as in Method 2is required in order to provide insulation. Although a single internal inverter section can be used for various supply voltages, different types of motor operation controllers need to be provided.
FIG. 32 is a circuit diagram of an insulation type bidirectional DC voltage converter disclosed in U.S. Pat. No. 5,027,264, wherein numeral 21 is a primary smoothing circuit, numeral 22 is a secondary smoothing circuit, numeral 100 is an insulation type bidirectional DC voltage converter, numeral 110 is a switching element controller of the insulation type bidirectional DC voltage converter 100, and numeral 120 is a voltage loop controller of the insulation type bidirectional DC voltage converter 100. The insulation type bidirectional DC voltage converter 100 comprises primary switching elements 101a-101d, an internal transformer 102, and secondary switching elements 103a-103d. Numerals i1, iL1, iL2, and i2 denote currents flowing in the arrow directions in FIG. 32 and V1 and V2 denote primary and secondary voltages respectively.
FIG. 33 is a block diagram showing an internal configuration example of the switching element controller 110 in, FIG. 32, wherein numeral 111 is a pulse generator, numeral 112 is a phase shift circuit for inputting phase difference ph and shifting the phase of an output pulse of the pulse generator 111 by phase difference ph, and numerals 113 and 114 are NOT circuits for inverting pulse signals. Assuming that a pulse generated by the pulse generator 111 is pls, the switching element controller 110 causes pls to be input to the primary switching elements 111a and 110d and inverted pls to be input to the primary switching elements 101b and 110c. Also, it causes pls whose phase is shifted by phase difference ph to be input to the secondary switching elements 103a and 103d and inverted pls whose phase is shifted by phase difference ph to be input to the secondary switching elements 103b and 103c. 
FIG. 34(a) is a block diagram showing an internal configuration example of the voltage loop controller 120 in FIG. 32, wherein numeral 121 is a subtractor for finding a difference between secondary voltage detection value V2 and secondary voltage target value V2* in the insulation type bidirectional DC voltage converter 100 and numeral 122 is a voltage loop gain circuit made up of, for example, a proportional element and an integrating element.
FIG. 34(b) is a flowchart representing the operation of the voltage loop controller 120 in FIG. 34(a). Secondary voltage V2 is input at step S101, voltage deviation V2er is calculated at step S102, phase difference ph, a controlled variable, is found at step S103, and the phase difference ph is output at step S104.
FIGS. 35 and 36 are timing charts and current waveform charts showing the operation state of primary and secondary drive circuits; FIG. 35 shows the power mode and FIG. 36 shows the regeneration mode. In the figures, signals 101a to 101d and 103a to 103d indicate the operation of the switching elements assigned the same reference numerals; the low pulse denotes the switch OFF state and the high pulse denotes the switch ON state.
Next, the operation will be discussed with reference to FIGS. 35 and 36. The insulation type bidirectional DC voltage converter 100 bidirectionally converts the primary DC voltage V1 into the secondary DC voltage V2 while insulating them from each other.
Since the primary switching elements 101a and 101d and the secondary switching elements 103b and 103c are ON in section a in FIG. 35, the primary current flows from the primary smoothing capacitor 21xe2x86x92switching element 101a internal transformer 102xe2x86x92switching element 101d- primary smoothing capacitor 21, applying voltage V1 to the primary winding of the internal transformer 102. Assuming that the turn ratio of the internal transformer 102 is n:l, voltage of about V1/n occurs on the secondary winding of the internal transformer 102 and a current flows from the internal transformer 102xe2x86x92switching element 103b secondary smoothing capacitor 22xe2x86x92switching element 103cxe2x86x92internal transformer 102. Assuming that the primary and secondary currents of the internal transformer 102 are iL1 and iL2 respectively, the current value iL2 is
iL2=nxc2x7iL1xe2x80x83xe2x80x83(1)
Now, if the leakage inductance of the internal transformer 102 is Lh and a sufficiently small value as compared with mutual inductance is set, iL1 is found with respect to ON time t according to the following expression:
iL1=(V1+nxc2x7V2)xc2x7t/Lhxe2x80x83xe2x80x83(2)
Now, assume that the phase overlap time is ph and that the current at the time is IL1x. As seen from Expression (2), the current increases in proportion to V1+nxc2x7V2 and thus increases in short time.
Next, in section b, the switching elements 103b and 103c are turned OFF and the primary current path is the same as described above; the secondary current flows from the internal transformer 102xe2x86x92switching element 103a (diode provided in conjunction with the element) secondary smoothing capacitor 22xe2x86x92switching element 103d (diode provided in conjunction with the element)xe2x86x92internal transformer 102. The direction of i2 is reversed. Therefore,
iL132 IL1x+(V1xe2x88x92nxc2x7V2)xc2x7t/Lhxe2x80x83xe2x80x83(3)
Assume that the current value at the time is IL1y.
Next, since the switching elements 101a and 101d are turned OFF in section c, the direction of the primary current is switched and the current flows from the internal transformer 102xe2x86x92switching element 101c (diode provided in conjunction with the element)xe2x86x92primary smoothing capacitor 21xe2x86x92switching element 101b (diode provided in conjunction with the element)xe2x86x92internal transformer 102. The secondary current is the same as described above. The current value decreases as in
iL1=xe2x88x92IL1y+(V1+nxc2x7V2)xc2x7t/Lhxe2x80x83xe2x80x83(4)
and continues to decrease until iL1=0.
Since the primary switching elements 101b and 101c and the secondary switching elements 103a and 103d are ON in section d, the primary current flows from the primary smoothing capacitor 21xe2x86x92switching element 101cxe2x86x92internal transformer 102xe2x86x92switching element 101bxe2x86x92primary smoothing capacitor 21. The secondary current flows from the internal transformer 102xe2x86x92switching element 103d secondary smoothing capacitor 22xe2x86x92switching element 103axe2x86x92internal transformer 102. The current value is the same as in Expression (2). Therefore, the current becomes IL1x at the same phase overlap time ph.
Next, in section e, the switching elements 103a and 103d are turned OFF and the primary current path is the same as described above; the secondary current flows from the internal transformer 102xe2x86x92switching element 103c (diode provided in conjunction with the element) secondary smoothing capacitor 22xe2x86x92switching element 103b (diode provided in conjunction with the element)xe2x86x92internal transformer 102. The direction of i2 is reversed. Therefore, the current value is the same as in (3).
Next, since the switching elements 101b and 101c are turned OFF in section f, the direction of the primary current is switched and the current flows from the internal transformer 102xe2x86x92switching element 101a (diode provided in conjunction with the element)xe2x86x92primary smoothing capacitor 21xe2x86x92switching element 101d (diode provided in conjunction with the element)xe2x86x92internal transformer 102. The secondary current is the same as described above. The current value is the same as in Expression (4) and continues to decrease until iL1=0.
Next, the operation in the regeneration mode will be described. Since the motor operates as a generator in the regeneration mode, the secondary voltage V2 increases and power flows reversely from the secondary winding to the primary winding. First, the primary switching elements 101b and 101c and the secondary switching elements 103a and 103d are ON in section g in FIG. 36, thus the secondary current flows from the secondary smoothing capacitor 22 switching element 103axe2x86x92internal transformer 102 switching element 103dxe2x86x92secondary smoothing capacitor 22, applying voltage V2 to the secondary winding of the internal transformer 102. Voltage of about nxc2x7V2 occurs on the primary winding of the internal transformer 102 and a current flows from the internal transformer 102 switching element 101bxe2x86x92primary smoothing capacitor 21 switching element 101cxe2x86x92internal transformer 102. The current value is found according to the following expression:
iL1=(V1+nxc2x7V2)xc2x7t/Lhxe2x80x83xe2x80x83(5)
Now, assume that the phase overlap time is Tx and that the current at the time is IL1x. As seen from Expression (5), the current increases in proportion to V1+nxc2x7V2 and thus increases in short time.
Next, in section h, the switching elements 101b and 101c are turned OFF and the secondary current path is the same as described above; the primary current flows from the internal transformer 102xe2x86x92switching element 101a (diode provided in conjunction with the element)xe2x86x92primary smoothing capacitor 21xe2x86x92switching element 101d (diode provided in conjunction with the element)xe2x86x92internal transformer 102. The direction of i1 is reversed. Therefore,
iL1=xe2x88x92IL1x+(nxc2x7V231 V1)xc2x7t/Lhxe2x80x83xe2x80x83(6)
Assume that the current value at the time is IL1y.
Next, since the switching elements 103a and 103d are turned OFF in section i, the direction of the secondary current is switched and the current flows from the internal transformer 102xe2x86x92switching element 103c (diode provided in conjunction with the element)xe2x86x92secondary smoothing capacitor 22xe2x86x92switching element 103b (diode provided in conjunction with the element)xe2x86x92internal transformer 102. The primary current is the same as described above. The current value decreases as in
iL1=xe2x88x92IL1y+(V1+nxc2x7V2)xc2x7t/Lhxe2x80x83xe2x80x83(7)
and continues to decrease until iL1=0.
Since the primary switching elements 101a and 101d and the secondary switching elements 103b and 103c are ON in section j, the secondary current flows from the secondary smoothing capacitor 22xe2x86x92switching element 103cxe2x86x92internal transformer 102xe2x86x92switching element 103bxe2x86x92secondary smoothing capacitor 22. The primary current flows from the internal transformer 102xe2x86x92switching element 101dxe2x86x92primary smoothing capacitor 21xe2x86x92switching element 101axe2x86x92internal transformer 102. The current value is the same as in Expression (5). Therefore, the current becomes IL1x at the same phase overlap time ph.
Next, in section k, the switching elements 101a and 101d are turned OFF and the secondary current path is the same as described above; the primary current flows from the internal transformer 102xe2x86x92switching element 101c (diode provided in conjunction with the element)xe2x86x92primary smoothing capacitor 21xe2x86x92switching element 101b (diode provided in conjunction with the element)xe2x86x92internal transformer 102. The direction of i1 is reversed. Therefore, the current value is the same as in (6).
Next, since the switching elements 103b and 103c are turned OFF in section 1, the direction of the secondary current is switched and the current flows from the internal transformer 102xe2x86x92switching element 103a (diode provided in conjunction with the element)xe2x86x92secondary smoothing capacitor 22xe2x86x92switching element 103d (diode provided in conjunction with the element) internal transformer 102. The primary current is the same as described above. The current value is the same as in Expression (7) and continues to decrease until iL1=0.
Therefore, the currents i1, iL1, and i2 become trapezoidal waveforms as shown in FIGS. 35 and 36, and their transfer power P becomes approximately as follows:
P=(average current of i2)xc3x97V2=nxc2x7IL1xc2x7V2 xe2x80x83xe2x80x83(8)
Thus, DC voltages can be converted bidirectionally in an insulated manner.
Next, the characteristics of the converter in FIG. 32 will be discussed. FIG. 37 is a graph showing the secondary voltage V2 when load resistor R0=3xcexa9 is connected to the secondary winding and the phase difference ph is changed on switching period Ts=50 xcexc s when the leakage inductance of the internal transformer 102, Lh, is 40 xcexcH, the turn ratio n is 2, and the primary voltage V1 is 600 V. As seen in FIG. 37, the secondary voltage V2 can be controlled by changing the phase difference ph.
Next, FIG. 38(a) shows the observation results of the secondary current iL2 of the internal transformer 102 when the primary voltages V1 are 150 V and 125 V by controlling the secondary voltage V2 fixed to 75 V with the turn ratio of the internal transformer 102, n, set to 2. The results indicate that when V1=nxc2x7V2, iL2 becomes a trapezoidal waveform, but when V1=/nxc2x7V2, iL2 does not becomes a trapezoidal waveform and the peak current of iL2 increases. FIG. 38(b) shows how the peak value of iL2 changes when the primary voltage V1 is changed under the same conditions as in FIG. 38(a). Thus, by performing phase difference control of the insulation type bidirectional DC voltage converter in FIG. 32, the peak current increases except when the relationship of V1=nxc2x7V2 holds.
We have discussed the insulation type bidirectional DC voltage converter using a single-phase transformer shown in FIG. 32. In U.S. Pat. No. 5,027,264, a three-phase insulation type bidirectional DC voltage converter shown in FIG. 39 and a multi-phase insulation type bidirectional DC voltage converter are also described; they have characteristics similar to those described above.
Since the conventional motor operation controllers are thus configured, the following must be provided to accommodate various power supply voltages:
1. Different types of motor operation controllers and motors conforming to the supply voltages;
2. different types of transformers conforming to the voltage specifications and output capacity of motor operation controller and motor for each supply voltage; or
3. different types of motor operation controllers containing a DC voltage converter for a common motor. However, of machine development, productivity, inventory management, maintenance management, etc., arise.
Main power supply voltages for motor control are 300-600 VDC and are supplied to machines often coming in contact with human bodies, such as motors, thus a complete insulation mechanism is required between the input power supply and machine. For this purpose, additional transformers need to be provided in options 1 and 2 described above.
Since circuit parts, (based on withstand voltage and current capacity) are selected for motor operation controllers, motors, and transformers in response to the power supply voltage specifications, the outer dimensions, outside structure, and weight vary greatly depending on the power supply voltage. It is remarkably difficult to standardize the motor operation controllers, motors, and transformers.
Motor operation controllers, motors, and transformers need to be mounted on machines using a motor, such as plant machines and tool machines, conforming to their respective voltage specifications. Not only replacement of the motor operation controllers, motors, and transformers and wiring construction, but also changing of structures, outlines, and installation places of the machines is incident to changing of the voltage specifications.
The motor operation controllers and motors are electrically connected directly, and there is a high possibility that insulation deterioration will cause an electric shock accident to occur.
The insulation type bidirectional DC voltage converter disclosed in U.S. Pat. No. 5,027,264 is prone to become overcurrent and requires switching elements and an internal transformer with a large current capacity.
It is therefore an object of the invention to provide a motor operation controller which can accommodate different power supply voltages by changing a minimum circuit configuration using common motors, wiring, etc., and has an insulation structure between input power supply and the motors for providing the capability of bidirectional operation in power mode and regeneration mode.
It is another object of the invention to suppress overcurrent of the insulation type bidirectional DC voltage converter disclosed in U.S. Pat. No. 5,027,264.
According to the invention, there is provided a motor operation controller comprising a converter section having a rectifier for converting an AC power supply voltage into a DC voltage, a power supply inverter circuit for converting a DC voltage into an AC power supply voltage, and an insulation type bidirectional DC voltage converter and an inverter section for supplying power to a motor.
According to the invention, there is provided a motor operation controller comprising a converter section having a rectifier for converting an AC power supply voltage into a DC voltage, a power supply inverter circuit for converting a DC voltage into an AC power supply voltage, and a bidirectional DC voltage converter and an inverter section for supplying power to a motor, wherein the motor operation controller is divided into two blocks of the converter section and the inverter section, which are built in separate cases.
According to the invention, there is provided an insulation type bidirectional DC voltage converter comprising a first converter having switching elements for converting a first DC voltage into an AC voltage, a transformer having a primary winding connected to an AC voltage output of the first converter, and a second converter having switching elements for converting an AC voltage connected to a secondary winding of the transformer into a second DC voltage, wherein transfer power is controlled by performing drive phase difference control of all power transmission switching elements and some of power reception switching elements.
The insulation type bidirectional DC voltage converter according to the invention further includes a voltage control loop circuit for holding a ratio between primary and secondary voltages constant.
The insulation type bidirectional DC voltage converter according to the invention further includes a voltage control loop circuit for holding a difference between secondary voltage into which primary voltage is converted and secondary voltage constant.
The insulation type bidirectional DC voltage converter according to the invention further includes a voltage control loop circuit for achieving a desired control by selecting constant secondary voltage control, constant difference control between secondary voltage into which primary voltage is converted and secondary voltage, or constant primary-secondary voltage ratio control in response to operation state.
The insulation type bidirectional DC voltage converter according to the invention, wherein the operation state used to determine the control mode of the insulation type bidirectional DC voltage converter is transfer power, further includes a voltage control loop circuit for performing the constant secondary voltage control if the transfer power is small or performing the constant difference control between secondary voltage into which primary voltage is converted and secondary voltage or the constant primary-secondary voltage ratio control if the transfer power is large.
The insulation type bidirectional DC voltage converter according to the invention, wherein the operation state used to determine the control mode of the insulation type bidirectional DC voltage converter is primary voltage, further includes a voltage control loop circuit for performing the constant secondary voltage control if the primary voltage is higher than a setup value or performing the constant difference control between secondary voltage into which primary voltage is converted and secondary voltage or the constant primary-secondary voltage ratio control if the primary voltage is lower than the setup value.
The insulation type bidirectional DC voltage converter according to the invention further includes a voltage control loop circuit for controlling by changing a control system gain depending on the selected control method when one of constant primary-secondary voltage ratio control, constant difference control between the secondary voltage into which the primary voltage is converted and the secondary voltage, and constant secondary voltage control is selected for use.
The insulation type bidirectional DC voltage converter according to the invention further includes a voltage control loop circuit for defining a maximum value of a command change slope so that a command value of secondary voltage does not rapidly change when the control methods are changed when one of constant primary-secondary voltage ratio control, constant difference control between the secondary voltage into which the primary voltage is converted and the secondary voltage, and constant secondary voltage control is selected for use.
The insulation type bidirectional DC voltage converter according to the invention further includes a filter capable of attenuating a detected primary voltage ripple.
According to the invention, there is provided an insulation type bidirectional DC voltage converter comprising a first converter having switching elements for converting a first DC voltage into an AC voltage, a transformer having a primary winding connected to an AC voltage output of the first converter, a second converter having switching elements for converting an AC voltage connected to a secondary winding of the transformer into a second DC voltage, and a voltage control loop circuit for controlling primary and secondary voltages, wherein a pulse width is changed in response to a difference between the primary voltage and the primary voltage into which the secondary voltage is converted.
According to the invention, there is provided a motor operation controller comprising a converter having a rectifier for converting an AC power supply voltage into a DC voltage, a power supply inverter circuit for converting a DC voltage into an AC power supply voltage, and an insulation type bidirectional DC voltage converter and an inverter section for supplying power to a motor, wherein when the power is turned on, the rectifier and the insulation type bidirectional DC voltage converter are operated at the same time.
The motor operation controller in the invention, which comprises an insulation type bidirectional DC voltage converter, can convert a converter section output voltage into a DC voltage in a given range for different power supply voltages and can make bidirectional voltage conversion.
The motor operation controller in the invention is divided into two blocks of a converter section for making bidirectional voltage conversion to a DC voltage in a given range for different power supply voltages and an inverter section, which are contained in separate cases. Thus, different power supply voltages can be accommodated by changing only the converter section without changing the motor, inverter, wiring, etc.
The insulation type bidirectional DC voltage converter in the invention controls transfer power by performing drive phase control of the power transmission switching elements and power reception single-side arm switching elements of the internal transformer. Thus, the current waveform slope can be reduced by half for improving controllability.
Since the secondary voltage is controlled in proportion to a change in the primary voltage, the maximum current can be suppressed even if the primary voltage changes.
Since control is performed so as to hold constant the difference between the secondary voltage into which the primary voltage is converted and the secondary voltage, the maximum current can be suppressed for a change in the primary voltage or an inverter section output change.
Since control is performed by selecting the constant secondary voltage control, constant difference control between secondary voltage into which primary voltage is converted and secondary voltage, or constant primary secondary voltage ratio control in response to the operation state, the maximum current can be suppressed in response to a condition such as a power supply voltage change or motor output change.
Since control is performed by selecting the constant secondary voltage control for light output or the constant difference control between secondary voltage into which primary voltage is converted and secondary voltage or constant primary-secondary voltage ratio control for heavy output, the maximum current can be suppressed for a power supply voltage change or motor output change.
Since control is performed by selecting the constant secondary voltage control when the primary voltage is higher than a setup value or the constant difference control between secondary voltage into which primary voltage is converted and secondary voltage or constant primary-secondary voltage ratio control when the primary voltage is lower than the setup value, the maximum current can be suppressed when the power is turned on or is abnormal.
When the constant secondary voltage control is performed, the gain is raised properly and when the constant difference control between secondary voltage into which primary voltage is converted and secondary voltage or constant primary-secondary voltage ratio control is performed, the gain is suppressed. Thus, when the constant secondary voltage control is performed, a fast voltage loop response can be made and when the constant difference control between secondary voltage into which primary voltage is converted and secondary voltage or constant primary-secondary voltage ratio control is performed, a ripple of the primary voltage can be prevented from causing the current to vibrate.
When one of the constant secondary voltage control, constant difference control between the secondary voltage into which the primary voltage is converted and the secondary voltage, and constant primary-secondary voltage ratio control is selected for use, the maximum value of the command change slope of the command value of the secondary voltage is defined at the time. Thus, excessive current occurring due to a rapid change in the secondary voltage command can be suppressed.
When the constant primary-secondary voltage ratio control or the constant difference control between the secondary voltage into which the primary voltage is converted and the secondary voltage is performed, a detected primary voltage ripple is attenuated by means of the filter. Thus, the primary voltage ripple can be prevented from causing the current to vibrate.
The maximum pulse width required for the current to become the setup maximum peak current is calculated from the difference between the primary and secondary voltages of the insulation type bidirectional DC voltage converter, and the upper limit of the pulse width is restricted. Thus, the maximum current can be suppressed when the power is turned on or voltage drops.
In the motor operation controller in the invention comprising a converter having a rectifier for converting an AC power supply voltage into a DC voltage, a power supply inverter circuit for converting a DC voltage into an AC power supply voltage, and an insulation type bidirectional DC voltage converter and an inverter section for supplying power to a motor, when the power is turned on, the rectifier and the insulation type bidirectional DC voltage converter are operated at the same time for making primary and secondary voltage changes at the same time. Thus, excessive current can be suppressed.